One year after receiving a life sentence for the murder of 270 people, the Libyan man convicted of the 1988 bombing of Pan Am Flight 103 over Lockerbie, Scotland, was back in court Wednesday for his appeal.

For the first time in Scottish legal history, judges have allowed a court proceeding to be broadcast live on television.

This appeal hearing is the final legal round for convicted Lockerbie bomber Abdel Basset al-Megrahi. He sat in court in traditional clothing listening as his lawyers made detailed legal arguments as to how they would challenge the original judges' interpretation of the evidence.

The burden of proof is now on them to convince the five Scottish appeals judges, who also serve as the jury, that their client's conviction and life sentence were a miscarriage of justice.

Scottish legal expert John Grant says it will not be easy.

"The court has already written an 82-page opinion, and if you read it in total it's quite compelling. And I can't quite see five judges readily overturning a decision taken with some care by three judges," said Mr. Grant.

But defense lawyers told judges they have significant new evidence.

Former Heathrow airport security guard Raymond Manly, they say, can testify that there was a break-in near Pan Am's baggage facility before the New York-bound flight took off from London 14 years ago. That is meant to cast doubt on where the bomb was placed and al-Megrahi's role in getting it aboard the plane.

Defense lawyers say the evidence was not presented during the trial because they did not know it existed. They are asking judges to let them submit it now.

A group of Arab lawyers disagree. They say they've come to Camp Zeist to give moral support to al-Megrahi, who they believe is innocent.

Al-Megrahi's family is also here. His son, Ali, who is not old enough to attend the proceedings, held up a sign outside the courthouse for his father. It read, "It is cold here and we have plenty of homework, but we're here for you."

Another son was asked what his father told him. He answered that he always told him he was innocent, he repeated he was innocent. And then they asked him what he thought and he said "I am very optimistic, I believe in my father's innocence," in remarks translated by Tunisian lawyer Abdel Hafidh Ellouze.

Judges still have to decide whether they will allow the defense's new evidence to be admitted. It is evidence that al-Megrahi's lawyers say will overturn his conviction. The whole appeal is expected to take four to six weeks.